1. Field of the Invention
The present invention relates to an inkjet ink and a recording unit.
2. Description of the Related Art
It has been known that the state of the surface having ejection orifices (hereinafter referred to as face side) of a recording head from which an inkjet ink (hereinafter referred to as simply ink) is ejected is changed as the ink is ejected. Particularly when an ink containing a pigment dispersed by a resin is used, the resin is gradually adsorbed to the face side of the recording head as the ink is ejected. Consequently, the surface characteristics of the face side are changed. The change of the surface characteristics of the face side may be referred to as face wetting. If an ink is ejected from ejection orifices of a recording head at which face wetting has occurred, ink droplets may land on positions different from intended positions where the ink droplets should land, thus producing a scrambled image. The phenomenon producing a scrambled printed image may be referred to as landing misalignment of ink droplets.
Japanese Patent Laid-Open No. 2004-269800 proposes a technique for reducing the landing misalignment by appropriately setting the surface tension of the ink and the contact angle between the face side of the recording head and the ink from which 20% or more of volatile component has been removed.
As a result of a study of this technique, the present inventors have successfully reduced the degree of face wetting to a specific level. However, an ink capable of further suppressing face wetting is desired in connection with a recent demand for more high-quality images.